[Java GUI] 筛选指定区间内满足条件的数字

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;

class NumberFrame extends JFrame implements ActionListener {

private static final long serialVersionUID = -8079275721169313862L;

private JLabel lblInfo = null;
JTextField txtStart;
JTextField txtEnd;
JTextField txtFactor;
JTextArea txtRes;
JButton btnCalc;
JPanel inputPanel;
JScrollPane resultPane;
JPanel panel;

NumberFrame(String title) {
super(title);
lblInfo = new JLabel("Number Game", JLabel.CENTER);
Container cp = getContentPane();
cp.add(lblInfo, BorderLayout.NORTH);

txtStart = new JTextField();
txtEnd = new JTextField();
txtFactor = new JTextField();

panel = new JPanel();
panel.setLayout(new BorderLayout());

JPanel lblPane = new JPanel();
lblPane.setLayout(new GridLayout(4, 1));
lblPane.add(new JLabel("From"));
lblPane.add(new JLabel("To"));
lblPane.add(new JLabel("Factor"));
lblPane.add(new JLabel());

JPanel txtPane = new JPanel();
txtPane.setLayout(new GridLayout(4, 1));
txtPane.add(txtStart);
txtPane.add(txtEnd);
txtPane.add(txtFactor);
btnCalc = new JButton("Compute");
btnCalc.addActionListener(this);
txtPane.add(btnCalc);

// input panel
inputPanel = new JPanel();
inputPanel.setLayout(new BorderLayout());
inputPanel.add(lblPane, BorderLayout.WEST);
inputPanel.add(txtPane, BorderLayout.CENTER);

panel.add(inputPanel, BorderLayout.WEST);

// result panel
txtRes = new JTextArea(150, 10);
txtRes.setLineWrap(true);
resultPane = new JScrollPane(txtRes);
panel.add(resultPane, BorderLayout.CENTER);

cp.add(panel);

setSize(400, 150);
setLocation(300, 200);
setResizable( false );
setVisible(true);
}

@Override
public void actionPerformed(ActionEvent e) {
if (e.getSource() == btnCalc) {
txtRes.setText(null);
try {
int m = Integer.parseInt(txtStart.getText().trim());
int n = Integer.parseInt(txtEnd.getText().trim());
int factor = Integer.parseInt(txtFactor.getText().trim());

for (int i = m; i <= n; ++i) {
if (i % factor == 0)
txtRes.append(String.valueOf(i) + " ");
}
} catch (NumberFormatException e1) {
e1.printStackTrace();
}
}
}
}

public class EvenNumberDemo {
public static void main(String[] args) {
new NumberFrame("Number Game");
}
}